Aircraft typically have displays to be seen by the aircraft pilot and other passengers of the aircraft. A pilot may be limited in moving their head within a headbox, and thus views the display within a certain angular range (viewing envelope). Thus the pilot may view the display only within a viewing angular range.
Stray light from displays can cause distracting reflections from windscreens, such as cockpit canopies. The stray light may be particularly problematic in night operations of the aircraft. On the other hand, stray light is typically not a problem during daytime viewing, and thus controlling stray light during daytime may not be needed or desired